I will write the code for you in PHP. Let's assume your first textfield name is textbox1 and you submit the form.
<?php
$txtbox_value = $_POST['textbox1'];
$splited_array = split('&', $txtbox_value);
values = '';
$i=0;
foreach($splited_array as $item){
if($i!=0){
$values .= $item.'\n';
}
$i++;
$i++;
}
echo '<textarea>'.values.'</textarea>';
?>
$i++;